Substrate processing apparatuses that perform various types of processing on substrates have conventionally been used in the process of manufacturing semiconductor substrates (hereinafter, simply referred to as “substrates”). For example, Japanese Patent Application Laid-Open No. 2010-93230 (Document 1) discloses a batch-type substrate processing apparatus that processes a plurality of substrates by one operation. With this substrate processing apparatus, a plurality of substrates held in a horizontal posture and arranged along the thickness (hereinafter, referred to as a “thickness direction”) of the substrates are carried into the apparatus by a batch hand. Then, a posture changing mechanism changes the posture of the plurality of substrates to a vertical posture at once and then collectively transfers the substrates to a pusher. Moreover, a new plurality of substrates are carried into the apparatus, and after the posture of these substrates are changed to a vertical posture, the substrates are transferred at once to the pusher that already holds another plurality of substrates. At this time, each of the substrates already held by the pusher (hereinafter, referred to as a “first substrate group”) is disposed between each pair of the new substrates (hereinafter, referred to as a “second substrate group”).
This substrate processing apparatus also includes a substrate-direction alignment mechanism for aligning the directions of a plurality of substrates that are held in a vertical posture by a chuck. The substrate-direction alignment mechanism aligns a plurality of substrates so that the orientations (i.e., circumferential positions) of notches provided in peripheral portions of the substrates match one another.
Japanese Patent Application Laid-Open No. 2008-78544 (Document 2) discloses an example of the structure of a substrate alignment apparatus. This substrate alignment apparatus aligns a plurality of substrates by rotating a plurality of substrates held in a vertical posture via a driving roller and stopping the rotation when a notch of each substrate has engaged with an engagement shaft that extends in the direction of arrangement of the substrates.
Meanwhile, a method for manufacturing a semiconductor disclosed in Japanese Patent Application Laid-Open No. H7-307319 (Document 3) aims to prevent, for example, the development of flaws caused by contact between a plurality of wafers due to the wafers possibly becoming warped during heat treatment. In the method, a plurality of wafers are classified according to their direction of warpage, and wafers warped in the same direction are housed in a single port and subjected together to heat treatment.
By the way, substrates processed by a substrate processing apparatus may be warped under the influence of processing performed before transport to the substrate processing apparatus, as described in Document 3. The sizes in the thickness direction of warped substrates are larger than those of flat substrates. When each of the substrates in the first substrate group is disposed between each pair of the substrates in the second substrate group as in Document 1 and if, for example, the substrates in the first substrate group and the substrates in the second substrate group are warped and convex in opposite directions, adjacent substrates may come into contact with one another due to the presence of portions where the distance between adjacent substrates is small.